PART 3 Natural Heritage Features and Landscape

Transcription

1 PART 3 Natural Heritage Features and Landscape PAGE 63

2 PAGE 64

3 3 NATURAL HERITAGE FEATURES AND LANDSCAPE 3.1 LAND, LANDFORMS AND LANDSCAPE The WRHA Act identifies a number of features in Section 7 National significance and Heritage Features of the Waitakere Ranges Heritage Area that relate to landform and landscape in the Waitakere Ranges and foothills: The relevant features are: Section 7(2)(b) Different classes of natural landforms and landscapes that contrast and connect with each other, and collectively give the area its distinctive character; Section 7(2)(f) The dramatic landform of the Ranges....; Section 7(2)(e) The quietness and darkness of the Ranges; Section 7(2) (i) the subservience of the built environment to the area s natural and rural landscape, which is reflected in (i) the individual identity and character of the coastal villages and their distinctive scale, containment, intensity, and amenity; and (ii) the distinctive harmony, pleasantness, and coherence of the low-density residential and urban areas that are located in regenerating (and increasingly dominant) forest settings; and (iii) the rural character of the foothills to the east and north and their intricate pattern of farmland, orchards, vineyards, uncultivated areas, indigenous vegetation, and dispersed low-density settlement with few urban-scale activities: The Land (Geology) Today s Waitakere Ranges are the extensively eroded eastern flank of the Waitakere Volcano dating back to the early Micocene period between 22 and 15 million years ago. In that period, the Australia and Pacific tectonic plates collided and a massive volcano, called the Waitakere Volcano was pushed up out of the sea. The volcano was 60 kilometres across and 40 kilometres from north to south, making it the second largest volcano that has ever erupted in New Zealand. Two lines of volcanic vents began erupting on the uplifted eastern flanks, one of these along the west coast. Striking features of the west coast formed by the volcanic vents include the cliffs at O Neills Bay. In some places magma flowed out onto the slopes of the volcano, producing flows under the ocean that created pillow lava, an example of which can be found at the south end of Bethells Beach. About 20,000 years ago when sea level was about 130m lower, the Waitakere River and its tributaries flowed seaward through a deep valley now buried beneath the beach. When sea level rose to its present level about 7000 years ago, the lower Waitakere Valley would have been flooded by the sea, forming a small harbour with arms extending up the Wainamu and Mokoroa valleys. Subsequently, long shore drift has dumped sand across the harbour entrance and some has blown inland and dammed a number of valleys to form lakes Wainamu, Kawaupaku and Waitakere. Lake Wainamu PAGE 65

4 The Waitakere Lake was all but filled by silt carried down by the Waitakere River and off the adjoining hillsides during bush clearance, and owing to the reduced flows in the river following the damming of the river upstream for water supply to Auckland in The lake was known as the lagoon in the first part of the 20 th century, and is now known as the Te Henga wetland. The map at Figure 12 shows the distribution of rock types at the surface in the Waitakere Ranges. Bethells/ Te Henga/ Waitakere Valley consists mainly of coarse volcaniclastic slope faces and terrestrial andesite flows, with a number of submarine lava flows and several crater complexes off the coast. Rock formation at O Neils Beach Photo: J Macdonald Figure 12: Simplified geological map of the Waitakere Ranges showing the distribution of rock types at the surface. Reproduced with permission. PAGE 66

5 3.1.2 Land Use The land use capability map at Figure 13 shows the quality of the land for agricultural purposes. Land with high agricultural value is ranked in class 1-3 (orange, green and red). Moderate value is from 4-6 (purple and blue) and poor value land is ranked 7-8 (black-grey stripes and brown). The map illustrates that Bethells/Te Henga/ Waitakere Valley has generally poor to moderate quality land for agricultural purposes, although as the early Maori in the area and present day residents well know, there are pockets of soils, particularly along the valley floor, that are particularly good for gardens and the growing of kumara and gourds. Te Aute Ridge Currently much of the cleared land is in pastoral land uses, with a mix of well-maintained and low quality farmland and some practices that may be considered unsustainable in such an ecologically sensitive area. Farmland along Bethells Road Figure 13 Land Use PAGE 67

6 3.1.3 Landform Features The policy section of the Waitakere City District Plan contains a number of relevant maps, including Landforms in Waitakere City and Outstanding Natural Features in Waitakere City. The coastal area is classified as western coastline cliffs, beaches and dunes, while the valley is dissected stream valleys with alluvial valley bottoms. The outstanding natural features of the area include: South Te Henga pillows and hyaloclastites Well exposed pillow lavas and hyaloclastites of national importance in the coastal cliffs surrounding points on either side of Wigmore Bay, south end, Te Henga Beach. O Neil Bay exposed strata exposed strata on an almost horizontal sequence at O Neill Bay, is a landform of regional significance Te Henga Valley deposition of sand has resulted in the formation of large mobile sand dunes, which extend approximately 2 kilometres inland associated with the formation of dune lakes (Wainamu, Kawaupaka and Waiataru) and the Te Henga Wetland. This association of landforms is of regional significance as it is unique in the Auckland Region. Pillow lava, south end, Bethells Beach Drawing by Mary Taylor Source: Waitakere Ranges Protection Society ( 1978) Wainamu-Te Henga A Study. Dune-impounded Lakes two lakes, Lake Wainamu and Lake Kawaupaku, formed by damming of the valleys by active sand dunes, well defined and little modified by humans. These lakes are of regional importance. Waitakere (Te Henga) Wetland originally a lake, the wetland occupies the lower reaches of the Waitakere River and Mokoroa stream, and is of regional and national significance as the largest freshwater wetland in the Auckland Region. Sand dunes near Lake Wainamu Photo: Olaf Peterson 1976 Waitakere Falls Te Awa Kotuku, or the plume of the White Heron. Waterfalls are a feature of the catchments of the river valleys of the Waitakere Ranges; the Waitakere Falls, below the Waitakere Dam on the Waitakere River, is among the better examples. Since the Waitakere Dam was constructed above the falls, there is no longer the same volume of water over the falls. Huia steepland soils Lake Wainamu Scenic Reserve, 2 kilometres east of Bethells Beach is also the site of Huia steepland soils, of which good examples are uncommon. PAGE 68

7 3.1.4 Landscape As in the past, landscapes which display little evidence of human presence, intervention or management and are dominated by natural elements are widely regarded as outstanding. Added to these, however, are some landscapes which are managed, including areas of pasture. The absence or visual subservience of buildings was an important component of these outstanding landscapes. Bethells Beach and Wigmore Bay (foreground) The Regional Policy Statement defines most of the Bethells/ Te Henga/ Waitakere Valley area as outstanding natural landscape (Refer Figure 14). This landscape work was originally derived from a 1984 landscape assessment undertaken by the ARC. Proposed Plan Change 8 to the Regional Policy Statement, notified in 2005, introduced changes as a result of a new regional landscape study completed in This study also classifies most of the Bethells/ Te Henga area as Outstanding Natural Landscape. Melean Absolum Limited undertook research for Waitakere City in comparing the two outstanding landscape maps (from 1984 and 2005) and analysing areas of difference. The results of this work in the Bethells/ Te Henga/ Waitakere Valley area are set out in Figure 15. Of note are the areas that are no longer classified as outstanding landscape. As can be seen in Figure 15, there are five areas that were re-classified in this time so that they are no longer considered outstanding landscape. In four of these cases, the probable reason is given as further development in the area. Areas that were included in the 2005 study that had been excluded in the 1984 study were mainly changed due to an identifiable change in the public s perception of the creation of an outstanding natural landscape (so that, for example, the Te Henga Wetland is now perceived as having outstanding landscape values), and the growth of vegetation. 25 Melean Absolum Ltd landscape Architects (October 2005) ARPS Plan Change 8 Outstanding Natural landscapes: Review for Waitakere City Council. PAGE 69

8 Figure 14: Auckland Regional Policy Statement Outstanding Natural Landscape Outstanding Natural Landscape PAGE 70 Te Henga Wetland Photo: J Macdonald

9 Figure 15: Bethells Area Comparison of Outstanding Landscape Classifications 1984 and 2005 The Waitakere City District Plan policy section contains a number of maps relevant to landscape, including Outstanding (Natural Character) Coastal Area, Landscapes of Waitakere City, Outstanding Landscapes of Waitakere City, Natural Landscape Elements and Views in Waitakere City. In these maps also, much of the lower valley area is identified as outstanding landscape and outstanding (natural character) coastal area. The settled areas are, in general, excluded from the area of outstanding landscape. Natural landscape elements include a number of sensitive ridgelines (as marked in the District Plan Natural Areas maps), wetlands and lakes, a dune system, headlands and islands. Views are identified from Te Aute Ridge Road West, and from Bethells Road around one kilometre back from the village, where the road rounds a hairpin bend atop a ridge. First view of the sea, from the hairpin bend in Bethells Road. Photo: Melean Absolum In 2006 Melean Absolum Limited was commissioned to identify and assess the character and sensitivity of landscape units in rural Waitakere and the potential for development and restoration. The study Rural Landscape Assessment identified four distinct rural landscape units within the Bethells/ Te Henga/ Waitakere Valley area, as described below. PAGE 71

10 Upper Bethells /Waitakere Valley A highly sensitive visual landscape with extensive native vegetation on the higher slopes. The potential for sensitive development is low due to the level of existing residential development and openness of the valley. Some potential for restoration exists in the stream valley and on abandoned agricultural land Middle Bethells/ Waitakere Valley A highly sensitive visual landscape, with steep north facing land from Te Aute Ridge to Waitakere River Valley and across to bush clad hills on the opposite side of the Valley. Very low development and restoration potential exists and minimum subdivision standards mean there is little capacity for further development. South Te Aute Ridge A highly sensitive landscape with steep bush clad slopes visible from Te Henga coastal village and the Wainamu dunes. While intensive residential development is visible on Bethells and Tasman View Roads, the area has low development potential. There is potential for restoration on abandoned agricultural land and on the large properties management areas (LPMA). Lower Bethells/ Waitakere Valley Strongly influenced by the Te Henga Wetland, pastoral farming and lifestyle blocks dominate the landscape unit. A highly visually sensitive landscape; there is little opportunity for development although some residential development could be realised on the bush clad slopes. Restoration potential exists on abandoned agricultural properties but is low elsewhere in the unit. A more in depth landscape assessment of the Bethells/ Te Henga area in the lower Waitakere Valley was completed in 2007 by Melean Absolum 26 (attached at Appendix 1) This report describes this area as follows: The Bethells Beach settlement comprises two small cul-de-sac extending eastwards from Bethells Road on the flatter land at the foot of the hills. Another cluster of residential settlement is on the bush clad slopes above the original Maori settlement, extending along the west-facing slopes above Bethells Road. Finally, a group of larger rural residential properties have been developed at the hairpin bend where Bethells Road turns sharply southwards and views of the sea are first seen. There is only one road in and out of Te Henga / Bethells and this corner The warning surfboard sign on Bethells Road. Photo: Melean Absolum and its tantalising view of the sea in the distance marks the edge of the settlement. A secondary entry point has more recently been marked by means of a warning surfboard. 26 Melean Absolum Ltd landscape Architects (2007) Waitakere City s Coastal Villages Landscape Assessment: Part 2 A study for Waitakere City Council. PAGE 72

11 Absolum (2007) divides the fourth of the rural landscape units identified in the 2006 landscape study the Lower Bethells/ Waitakere Valley landscape unit - into six further landscape units. Steep vegetated slopes separate the different clusters of housing from each other, creating the boundaries of the different landscape units. The 6 landscape units are mapped A to F at Figure 16. The landscape assessment for each of these areas is summarised below: Bethells A Landscape Unit A encompasses the more recently developed group of rural residential properties on the hairpin bend on Bethells Road. They are located on a low spur which extends westwards into the Te Henga Wetland. This area is unlikely to see further redevelopment as there is little capacity for further subdivision. Continued management of the riparian edges of the wetland is proposed to inhibit re-establishment of willows. Bethells B Little to no development potential exists in this unit as all vacant sites appear to have been developed. The bush clad land behind the houses to the east acts as a dense buffer to houses on Tasman View Road. There is some potential for restoration on the higher slopes; however the small section size of many properties means ecological advantages are limited. Bethells C Data from 2003 shows several vacant sites in the bush living environment around Tasman View Road, but further subdivision is unlikely. The area is vulnerable to incremental loss of native vegetation. Little restoration is necessary in this area apart from enhancement of the road corridors through minor weed management. Bethells D Pastoral properties dominate the flatter land around the confluence of Waiti Stream and Waitakere River. Several large properties exist; these could be subject to subdivision in Tasman View Rd ridge 2010 the future. Residential development on some properties may be hindered by the Waitakere River floodplain and wetland. Potential for restoration exists on the edges of the waterways as well as weed control on the roadside and parking areas. Bethells E Subdivision in the 1970s has resulted in a coastal village environment with suburban infrastructure such as kerbs and footpaths, but these are low key in character. Any redevelopment of residential properties could see the introduction of much larger and prominent homes and the area is vulnerable to urbanisation through inappropriate introduction of urban design solutions. Some potential exists for development. Bethells F The area is defined by dwellings clustered around Lake Waiataru and along hill slopes to the north, within several Large Property Management Areas (LPMA). Further vegetation removal has the potential to remove screening elements and also increase erosion potential. Little potential to develop sites exists. The potential for lakeside restoration enhancement around Lake Waiataru and the southern edge of the unit has been identified through a LPMA Conclusion Land, Landforms and Landscape The Bethells/ Te Henga/ Waitakere Valley area has a wealth of outstanding natural features and landforms, including two dune impounded lakes of regional significance and the Te Henga Wetland, the largest wetland in the Auckland Region and of national significance. Most of the area, except for the grassed areas alongside Bethells Road on the valley floor, is PAGE 73

12 classified as outstanding natural landscape and outstanding (natural character) coastal area. The entire area is considered highly visually sensitive with low development potential Figure 16 Coastal Landscape Units at Bethells/ Te Henga PAGE 74

13 3.2 ECOLOGICAL FEATURES The Bethells/ Te Henga area (together with much of the rest of the Heritage Area) is outstanding in northern Waitakere Valley, New Zealand for the extensive and intact nature of its lowland and coastal forest ecosystems, and associated dune and wetland systems. It contains distinctive and outstanding plant species and communities, fauna and landscapes. Terrestrial and aquatic ecosystems are identified as heritage features in the WRHA Act: Section 7 (2) The heritage features of the heritage area are (a) its terrestrial and aquatic ecosystems of prominent indigenous character that (i) include large continuous areas of primary and regenerating lowland and coastal rainforest, wetland, and dune systems with intact ecological sequences: (ii) have intrinsic value: (iii) provide a diversity of habitats for indigenous flora and fauna: (iv) collect, store, and produce high quality water: (v) provide opportunities for ecological restoration: (vi) are of cultural, scientific, or educational interest: (vii) have landscape qualities of regional and national significance: (viii) have natural scenic beauty: The naturally functioning streams and the water supply dam in the area are also heritage features (s7(2)(d) and (n)). Water features are dealt with in section 3.3 below Ecological units The study area is part of the Waitakere Ecological District. The report Ecology of Waitakere s Rural Areas by Kingett Mitchell Ltd 2007 identifies four ecological units in the Bethells/ Te Henga/ Waitakere Valley area. The Bethells Valley Ecological Unit (refer Figure 17) extends along the north western boundary of Waitakere City from the lower reaches of the Te Henga Wetland to the ridge above the Waitakere Quarry. The Waitakere Stream forms the northern boundary, which broadens into the Te Henga Wetland in the lower reaches. The Valley is contiguous with a large forest tract in the Mokoroa Stream catchment. Within the valley, areas of mature kanuka are present. Following historic clearance and farming in the area these tracts have been left to regenerate. They connect to Te Henga Wetland Photo: Liz March remnant stands of cut over kauri and coastal broadleaf forest. Along roadsides and stream gullies in this ecological unit native scrub is regenerating and large (mostly exotic) trees form links between the bush areas. Due to the regional and national significance of the wetland in this unit, any changes in landuse that result in intensification of human activity pose significant risks of adverse cumulative effects to the wetland and surrounding areas. PAGE 75

14 Figure 17- Ecological Units- Bethells Valley Source: Kingett Mitchell Ltd 2007 The Te Aute- Waiti Ecological Unit (refer map at Figure 17) follows South Te Aute Ridge with its steep, south facing slopes that drop down from Te Aute Ridge Road to the stream beds of Te Aute and Waiti Streams. The unit also includes the open pastoral land on the eastern headwaters and south of Te Aute Stream and north of Lake Wainamu. Small scattered fragments of kanuka scrub are present with erosion noticeable on steep, grassed slopes. Indigenous forest and scrub covers much of the remainder of the unit. A puriri composite forest remnant covers the northern slope above Waiti Stream and further up Te Aute Stream Valley the landscape is dominated by kanuka forest and scrub. This is interspersed with regenerating species including karaka, puriri, rewarewa, pigeonwood and mangaeo. Waiti Stream drains into a small freshwater wetland comprised mainly of raupo, cabbage tree and manuka. The Bethells Village Ecological Unit (refer map at Figure 17) comprises the more compact residential housing areas in the Valley. Inland dunes and the low hills behind the unconsolidated dune systems of Bethells Beach are also a significant part of the unit. Lake Wainamu and Lake Wainamu the catchment of Lake Kawaupaku form the eastern and southern boundaries with the lower reaches of the Waitakere River forming the northern boundary. There is a suburban character to the residential enclave, with grassed lawns and exotic ornamental gardens peppered throughout. There have been ongoing restoration and replanting efforts on Council land and extensive weed and pest control and restoration of the dune ecosystem. Since 1995 over 23 hectares of coastal vegetation on the dunes and water margins has regenerated (through active management and natural regeneration following the introduction of rabbit baiting in PAGE 76

15 2005). Pest control on the dune ecosystem has also seen the return of breeding pairs of Dotterels to the beach. Behind the village, pine forest is present on part of the hill slope. At some point the area appears to have been cleared for farming and now is covered in weeds including kikuyu, pampas, wilding pines and tree lupin. Figure 18 - Kawaupaku Dune and Hinterland Ecological Unit Source: Kingett Mitchell Ltd 2007 The Kawaupaku Dune and Hinterland Ecological Unit (refer map at Figure 18) is largely covered in indigenous forest and scrub. The area has been undisturbed for at least the past 60 years, allowing regeneration of indigenous vegetation to occur, following historic logging and clearing. The dune impounded lake forms the northern boundary and extends south towards Anawhata Road. A small settlement at the southern end of Bethells Beach is comprised of a group of residential dwellings, auxiliary buildings and open pastoral farmland. Because of its remote and inaccessible location the unit is largely unmodified. A narrow fringe of wetland vegetation is found on the margins of the lake. These include raupo, bamboo spike sedge, jointed twig rush and giant umbrella sedge. Also present are localised dense swards of giant reed. On the northern slopes of the lake pohutukawa forest dominates and is interspersed with puriri, rewarewa, karaka, mangaeo, nikau and kowhai. Tawapou has also been identified at this site (Denyer et al ). The remainder of the unit is covered in coastal broadleaf forest comprised of puriri, rewarewa, karaka, mangaeo, kanuka, nikau, kowhai and some clusters of pole kauri. Scattered remnants of scrub are interspersed with rimu, tanekaha, rewarewa, lancewood and occasional kauri. An extensive tract of coastal scrub (a low growing canopy of manuka and kanuka, with flax, hangehange, ngaio and cabbage trees scattered throughout) covers the headland and secondary kanuka scrub approximately 60 years old covers the Kawaupaku hinterland. 27 Denyer, K; Cutting M; Campbell G; Green C; Hilton M (1993), Waitakere Ecological District survey report for the Protected Natural Areas Programme. Auckland Regional Council, Auckland. PAGE 77

16 3.2.2 Recommended Areas for Protection Within the Ecological Units described above, discrete areas have been identified as Recommended Areas for Protection (RAPs). The Bethells/Te Henga/ Waitakere Valley area encompasses three RAPs. These RAPs were identified under the Protected Natural Areas Programme 1993, a New Zealand wide Department of Conservation programme developed as a way of ensuring that the range of natural features of New Zealand are conserved for the future. The survey for the Waitakere Ecological District was undertaken by Denyer et al (1993). Maps of the RAP areas are found in Appendix 2. Te Henga wetland Te Henga Valley (RAP 5) is a priority landform site that contains the Te Henga wetland, a wetland of regional significance. Vegetation types within the RAP include examples of young kauri forest, kauritanekaha forest, kauri-kanuka forest, puriri composite forest, ponga-broadleaf forest, kahikatea swamp and Baumea sedgeland. There is also an excellent example of seral succession (an important stage in ecological succession, often following disturbance) in a freshwater wetland ecosystem (transitioning from open water- floating vegetative mats, sedgeland- cabbage tree forest- terrestrial forest). Species present in the RAP include the threatened Australasian bittern and banded rail, the regionally threatened North Island fernbird, and the sparse spotless crake, marsh crake and the pukeko. Makutu Reserve is also home to three species of lizard, the Auckland green gecko, forest gecko and copper skink. Windswept vegetation on the North Te Henga coastline Photo: J Macdonald PAGE 78

17 The Northern Te Henga Coastline (RAP 6) consists of a stretch of rocky and sandy coastline incorporating two vegetated islands, a headland and vegetated hill slope of marine sand. Vegetation types include kanuka scrub on consolidated sand, pohutukawa forest, karo -houpara forest and flax-manuka scrub on the exposed rocky coast. A range of seabird species are present including colonies of grey faced petrel, sooty shearwater and diving petrel. Kauwahaia Island Photo: J. Macdonald The Te Henga Dunes and Lakes (RAP 7) is a large area of sand dune lakes surrounded by vegetated lowland hill country. It is a priority landform site of regional significance as it contains vegetated and mobile dunes, and dune impounded fresh water lakes. Vegetation types within the RAP include kanuka scrub and pohutukawa forest on unconsolidated (loose) sand, pohutukawa forest, kanuka forest and puriri composites forest on rugged hill country, raupo reedland and cabbage tree forest within a dune impounded lake system. The RAP is situated within a larger area containing a complex array of landforms including freshwater swamp, exposed sandy beach, rocky cliff coastline, dune sands, dune impounded lakes and rugged hill country of native forest and scrub. For the full list of outstanding vegetation sites in the Bethells-Te Henga/ Waitakere Valley area see Appendix 3. Lake Wainamu Indigenous Wildlife The Bethells-Te Henga Valley is recognised as a Site of Special Wildlife Interest (SSWI) for its outstanding fauna habitat. The SSWI were also identified as part of the Protected Natural Areas Programme The large area of continuous forest covering the ranges, the range of species including grey faced petrel colonies, kaka (which are frequently reported), pied tit, kereru and a number of other NZ bird species are present and all contribute to it being a PAGE 79

18 SWII. A diverse range of insect and snail fauna and other endemic species are found in the area. Roosting areas for the New Zealand long-tailed bat (Chalinolobus tuberculatus), a threatened endemic species, have been discovered in large, emergent trees (mainly Kauri) in the Cascade Kauri Park, although these bats have a wide foraging distribution. Source: Waitakere Ranges Protection Society (1978) Wainamu-Te Henga: A Study Conclusion: Ecological Features There are four Ecological Units in the Bethells/ Te Henga/ Waitakere Valley area, and within these, three Recommended Areas For Protection have been identified under the Protected Natural Areas Programme, a New Zealand wide Department of Conservation programme developed as a way of ensuring that the range of natural features in New Zealand are conserved for the future. These are the Te Henga Wetland, the North Te Henga Coastline (north of the Waitakere River Mouth) and the Te Henga sand dunes and lakes. The Bethells/ Te Henga/ Waitakere Valley is also recognised as a Site of Special Wildlife Interest for the range of bird species and the diverse range of insect and snail fauna and other endemic species that are found in the area. PAGE 80

19 3.3 STREAMS, WETLANDS LAKES AND RESERVOIRS Water bodies and aquatic ecosystems are identified as heritage features in the WRHA Act. Section 7 (2) sets out the heritage features of the heritage area that individually or collectively contribute to its significance. Relevant parts are: (a) its. aquatic ecosystems of prominent indigenous character that (i) include large continuous areas of. wetland, with intact ecological sequences: (d) the naturally functioning streams that contribute positively to downstream.. stormwater management, and flood protection: (n) the public water catchment and supply system, the operation, maintenance, and development of which serves the people of Auckland. This section describes these heritage features of the Bethells/ Te Henga/ Waitakere Valley area Rivers and Streams The Waitakere River flows from the head of the catchment in the hills around the Waitakere Reservoir in the Waitakere Ranges Regional Park water catchment area, down through Cascade Kauri Park, under Te Henga Road, and Bethells Road (at Black Bridge), and through the Te Henga Wetland to the sea. The main tributaries of the Waitakere River are the Cascade Stream system in Cascade Kauri Park, the Waitipu Stream draining the catchment north of Te Henga Road, and the Waiti/ Te Aute/ Wainamu Stream subcatchment, which joins the Waitakere River not far from the river mouth. On the northern side of the Te Henga Wetland, the Mokoroa stream is a major catchment flowing from Goldies Bush into the Waitakere River system. While it is outside the boundary of the Heritage Area and the proposed area for the LAP, any effects both positive and negative to this stream catchment need to be considered when determining policies and actions for the LAP. Waitakere River upstream of Te Henga Road Bridge Photo: J. Macdonald PAGE 81

20 Waitakere River Mouth Photo: J Macdonald Streams in the Waitakere River catchment include: Waitakere River Taimana Stream Anderson Stream Waiti Stream John Stream Cascade Stream Te Aute Stream Plum Pudding Stream Rumpus Gulley Stream Waitipu Stream Houghton Gully Bacon Stream Maioha Stream Brissendaon Stream Wipene Stream Koropotiki Stream Mosac Stream Koropotiki Stream Wainamu Stream Toetoeroa Stream Olaf Stream Papari Stream Gleeson Stream Houghton Gulley Stream Waitauri Stream Robinson Stream Kelly Stream As well as the Waitakere River catchment, there are a number of smaller stream catchments draining directly to the Tasman coast in the south of the study area, including the Taimana Stream from Lake Kawaupaku, the Happy Valley Stream and the Kuataika stream/ Cannibal Creek catchment. The stream systems are shown in the map at Figure 19. PAGE 82

21 Figure 19 Water Bodies in the Bethells/ Te Henga/ Waitakere Valley PAGE 83

22 3.3.2 Wetlands Te Henga Wetland Formation The Te Henga Wetland was originally a lake, much larger but otherwise very similar to Lake Wainamu. It was ponded by beach and dune sands across the valley mouth less than 6,000 years ago. Eroded material, brought down from the Mokoroa stream and Waitakere River had already filled it up quite considerably before the arrival of the first European settlers, although they referred to it as a lake, or lagoon. The wetland was still quite navigable in the main channels in the 1920s, when logs were towed by launch to its head in the Waitakere arm, from both the Mokoroa arm and the Waiti junction. Increased erosion following the clearing of the bush increased the rate of infill of the lake, and this was probably also hastened by the construction of the Waitakere dam and reservoir in its headwaters, which resulted in a greatly reduced flow through the swamp, allowing vegetation growth to increase. The building of a causeway constructed across the swamp in the 1970s also likely helped to increase the rate of infilling. PAGE 84

23 Te Henga Wetland Photo: J Macdonald Significance of the Te Henga Wetland The Te Henga Wetland at 153 hectares is the largest wetland in the Auckland Region and, according to a report by the National Institute of water and Atmospheric Research Ltd (NIWA) 28 is regarded as an area of national importance for wildlife species. It is part of Recommended Area for Protection (RAP) 5, described in section above. The wetland comprises predominantly indigenous vegetation including a large range of vegetation types and it also provides high quality fauna habitat. There are extensive areas of Baumea sedgeland, raupo reedland, swamp millet and cabbage tree forest. Bird species recorded include Australasian bittern, fernbird, spotless crake, banded rail and marsh crake. A range of native fish and aquatic invertebrates including the threatened giant kokopu have also been recorded. Land Tenure of the Te Henga Wetland The Te Henga wetland and its margins are mostly privately owned. As shown on the map at Figure 20, the Royal Forest and Bird Society own Matuku Reserve a 120 hectare site on the northern side, which can be accessed from Horsemans Road. The Fish and Game Council own a further hectares of land, mainly wetland, and the Rodney District Council hold an esplanade reserve along the western banks of the wetland. The Department of Conservation also have a marginal strip within the wetland. Te Henga Wetland Photo: J Macdonald 28 NIWA 1999, Waitakere Wetland: Recommendations for Management of Willows and other Plant Pests Client report WTK00203 PAGE 85

24 Figure 20: Te Henga Wetland Matuku Reserve and Fish and Game Council land Waiti Wetland The Waiti Stream drains into a small freshwater wetland in the north-western corner of the Wheeler property. A report by Kingett Mitchell (1997) 29 notes that although relatively small, this wetland is relatively intact and free of weeds (with the exception of pampas and bindweed) and comprises a good quality, representative example of a vegetation and habitat type which is under-represented due to drainage, reclamation and inappropriate use. This wetland also comprises good quality habitat for wetland birds. Small wetland at the junction of the Waiti and Te Aute Streams 29 Kingett Mitchell (1997), Ecological Values Assessment of the Wheeler Property for the Large Properties Project PAGE 86

25 3.3.3 Lakes and Reservoirs Lake Wainamu Lake Wainamu is a deep dune lake with a narrow vegetated band of raupo and Eleocharis. A range of wetland bird species are present including Australasian bittern and the North Island fernbird. Other species that have been recorded include black shag, little shag and various waterfowl species. Native fish species including banded kokopu, inanga, common smelt, common bully, grey mullet, long finned and short finned eel are all found in the lake. Lake Kawaupaku A deep dune lake with a maximum depth 23 metres, Lake Kawaupaku is completely enclosed by native bush which covers the whole of the relatively small surrounding catchment and is an area of high ecological value 30. A narrow margin of raupo, flaxes, rushes and sedges surrounds the lake and there are many large pohutukawa around the lake edge. There is a small cleared area of grass at the northern end, used by the family for picnics and swimming. Taimana Stream drains the lake out to the west through Nikau palms and coastal forest. Bird species present include little black shags, spotless crake and pukeko. Denyer et al. (1993) note that the coastal shrubland in this vicinity is good habitat for two species of native gecko Auckland green gecko and the forest gecko. There is no history of agriculture in the catchment. In the early days, the lake was tapu due to the proximity of Maori burial pits, the tapu being lifted in the 1920s. The lake itself is privately owned, with much of the catchment lying within the Waitakere Ranges Regional Park. Until 2003 the lake was used as a drinking water supply by local residents. Lake Waiataru Lake Waiataru is the smallest of the dune impounded lakes in the Bethells/ Te Henga area, and is in private ownership. Known locally as the duck pond, Lake Waiataru was a popular swimming spot in the early days of settlement, boasting a diving board. 30 Kingett Mitchell (1997), Ecological values Assessment of the Hooker Property for the Large Properties Project PAGE 87

26 Waitakere Dam The Waitakere Ranges are of importance for the critical contribution to Auckland's water supply. The area is a vital water catchment and the site of a series of storage dams and supply systems that have sustained Auckland s urban growth since The Waitakere dam is a concrete dam completed in 1910 to provide a water supply to the people of Auckland. The lake area is 25.1 hectares, and the capacity1.76 million cubic metres. Raw water is treated at the treatment plant located at the top of Christian Road in Swanson, before being piped to customers. Waitakere Dam and reservoir Photo: Water Care Services Ltd It is important to sustain the potential of the natural and physical resources of the Waitakere Ranges to meet current and future water needs of the community. The land surrounding the Waitakere Dam is part of the regional parks network, but is managed by Water Care Services Limited and designated in the District Plan for water supply purposes Conclusion: streams, wetlands, lakes and reservoirs The water resources in the study area comprise the Waitakere River and its tributaries, and two smaller stream systems draining directly to the Tasman Sea. The nationally significant Te Henga Wetland, in the lower reaches of the Waitakere River, is mostly privately owned, as is another small natural wetland on the Waiti Stream in the Wheeler property. Dune impounded lakes include Lakes Wainamu, Kawaupaku and Waiataru, the latter two located in private property. Lakes Wainamu and Kawaupaku are classified as outstanding natural features. The Waitakere Dam, on the upper reaches of the Waitakere River, was constructed in 1910 and provides good quality potable water supply to the City of Auckland. Waitakere Reservoir Photo: Dan Baker PAGE 88